A laminated glass is a safety glass which, even when broken by impact from the outside, shatters into few flying glass fragments. For this reason, a laminated glass is widely used for cars, rail cars, aircrafts, boats and ships, buildings, and the like. The laminated glass is produced by sandwiching an interlayer film for a laminated glass between a pair of glass plates.
Patent Document 1 provides one example of the interlayer film for a laminated glass; that is, Patent Document 1 teaches a sound insulation layer that contains 100 parts by weight of a polyvinyl acetal resin having a degree of acetalization of 60 to 85 mol %, 0.001 to 1.0 part by weight of at least one metal salt of alkali metal salts and alkaline earth metal salts, and 30 parts by weight or more of a plasticizer. This sound insulation layer alone can be used as an interlayer film.
Patent Document 1 also teaches a multilayer interlayer film in which the sound insulation layer and another layer are laminated. The another laminated on the sound insulation layer contains 100 parts by weight of a polyvinyl acetal resin having a degree of acetalization of 60 to 85 mol %, 0.001 to 1.0 part by weight of at least one metal salt among alkali metal salts and alkaline earth metal salts, and 30 parts by weight or less of a plasticizer.
Patent Document 1: JP 2007-070200 A